1. Field of the Invention
The present invention relates to a method and a device for producing an optical component and also to an optical component. More particularly, the present invention relates to a method and a device for molding an optical component to be used as a lens for spectacles or an optical appliance by pressurizing and distributing a plasticized raw material resin contained in a mold cavity, and also to an optical component produced by the producing method and producing device.
2. Description of Related Art
Methods for molding a resin optical component typically by means of injection compression molding are known (refer to, for example, Document 1: Japanese Patent Publication No. 3260072, and Document 2: International Publication WO99/24243 Leaflet).
The injection compression molding method of Document 1 is designed so that a molten raw material resin is injected into and filled in a mold body having a pair of lens molding cavities, a runner communicating with the cavities and a sprue communicating with the runner to mold a lens by compression molding.
In the molding method of Document 2 raw material resin of a lens (preform) is heated and the plasticized raw material resin is molded as a lens by compression molding.
However, the known injection molding methods are accompanied by drawbacks. For example, raw material resin is also filled in the runner and the sprue in addition to the lens molding cavities (Document 1) and raw material resin can spill out from the mold (see FIGS. 6 and 8 of Document 2), so that raw material resin is required by a volume greater than the volume essentially necessary for the molded product, or the lens, to make the known methods uneconomic. Furthermore, when, for instance, a molded product is used as a spectacle lens, only the central portion of the molded product corresponding to the profile of the frame of the spectacles is used. In other words, the remaining peripheral portion of the molded product is left unused and hence raw material resin is wasted.
Additionally, with the molding method of Document 2, the compressed raw material resin spills out of the mold so that, while the compressive force of the mold is applied to at the central portion of the lens, the compressive force is escaped to the outside at a peripheral portion of the lens to consequently degrade the optical characteristics of the peripheral portion of the lens.